In the fabrication of microelectronic components, a number of the steps involved, for instance, in preparing integrated circuit chips and the packaging for the chips (articles to which the chips are attached and protected), are etching processes. Accordingly, over the years, a number of vastly different types of etching processes to remove material. sometimes in selective areas, have been developed and are utilized to varying degrees. Moreover, the steps of etching different layers which constitute, for instance, the finished integrated circuit chip are among the most critical and crucial steps.
One method widely employed for etching is to overlay the surface to be etched with a suitable mask and then immerse the surface and mask in a chemical solution which attacks the surface to be etched, while leaving the mask intact and while only etching other materials of the article to at most, a minimum extent.
The problem of selectivity is especially pronounced when silicon dioxide is present on the same article as a silicate glass and is also exposed to the composition used to etch the silicate glass. This requires superior cleaning or etching solutions that exhibit extremely high selectivities in etching between the silicate glass and the silicon dioxide material.
It would therefore be desirable to provide a selective etching procedure that exhibits high selectivity for the silicate as well as achieving excellent removal.